a. Field of the Invention
The present invention relates to a method of treating leg weakness in poultry.
b. Description of the Prior Art
"Leg weakness" is a term used to describe a variety of abnormalities affecting locomotion in poultry. This weakness can result in an unwillingness of the birds to stand or walk and thus impair their ability to feed, which can result in starvation and even death.
Poultry farming has become an important area of agriculture and leg weakness in poultry has plagued the industry for many years and is of significant economic importance in breeding broilers, turkeys, etc. The losses due to foot and leg problems are estimated variably from 3-30%. The longer the rearing process, the greater the susceptibility of the poultry to leg weakness. This problem is particularly significant for commercial poultry breeders who operate their farms on a very tight schedule on a mass production basis. Thus the young chicks are received by the farmer and fed on a rigid schedule and with a specifically prepared feedstock which contains all the required nutrients for growth and weight gain. This process lasts, in the case of turkeys, for about 16-22 weeks, at which time the fully grown turkeys are transferred to the slaughterhouses. During this period there may be introduced into the feedstock speoifio vitamins or special nutrients or medications as the need arises, based on a monitoring of the health and growth rate of the birds. Since this process involves hundreds and even thousands of birds, any serious illness or disruption of the process with respect to individual birds affects total output, since it is difficult and at times impossible to identify and isolate, much less treat such exceptional cases.
Generally leg weakness appears in the case of turkeys after about 12 weeks. By this time the birds have grown significantly and put on substantial weight, which in some cases makes them too heavy for their legs and feet, causing inflammation and deformation thereof. Birds so affected find it difficult and painful to walk to their feeding troughs and tend to sit down, refusing to move. Apparently starvation is preferable to them than the pain and discomfort of seeking their food and drink. Once the birds have reached this stage, they lose weight and other birds attack it and eventually it dies. The farmer is not equipped to pull out these affected birds for individual treatment and thus they wind up as a loss to the overall yield of poultry product. What has happened in the industry is that the controlled breeding, feeding and management to produce higher growth rates is making the situation worse. The skeleton and the legs have to respond to the pressures of rapidly increasing weight and muscular tension.
Studies of leg weakness in poultry have shown that many nutritional deficiencies can cause these abnormalities, including several vitamin and mineral deficiencies. This however is not the case with modern poultry growing, since these nutrients are very much part of the controlled diet fed to birds. Thus B. Sauveur--Proceedings of the 7th European Poultry Congress, Paris, Volume 1:280, 1986--states that numerous studies have been devoted to the problems of leg weakness in poultry during the last 15 years without solving them. Progress has been made only in the classification of the types of leg abnormalities. Bar et al.--1987, Poult. Sci., 66:68--investigated 32 outbreaks of leg disorders in turkeys and concluded that the cause was a refractoriness to Vitamin D3. Recently Ibrahim et al. 1988. Brit. Poult. Scit., 29:721--assumed from his studies that the leg abnormalities are related to either or both mineral deposition and or collagen formation, with tannins acting either in the digestive tract or directly on the bone tissue. He was able to alleviate the problems by supplementing the feed with orthophosphoric acid or feed grade dicalcium phosphate.